Polarization-Induced Temperature Instability of HfO₂-Based Ferroelectric FET

We have investigated polarization-induced temperature instability (PTI) of HfO ₂ -based ferroelectric field-effect transistor (FeFET) and reveal its mechanisms. Since the existence of spontaneous polarization in ferroelectric, an internal bias emerges even without applied gate voltage, which results in performance degradation that can be accelerated under high-temperature stress (HTS). By systematically characterizing PTI, we find that FeFET suffers from strong positive PTI including subthreshold swing (SS), on-current (I _ON ), memory window (MW) and endurance degradation, however, negligible negative PTI is observed. In addition, the evolution of stable and reversible polarization (P _Sta and P _Rev ) with accumulated time of HTS is captured by quasi-static capacitance voltage (QSCV) method, which indicates the transition from P _Sta to P _Rev is responsible for the performance degradation by PTI.